Spark-plug.



J. S. OGARA.`

SPARK PLUG.

APPLICATION min Nov. 22. |917.

lut' \11tcdNov. 26, 1918.

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JOSEPH S. OGARA, OF LANCASTER, OHIO.

SPARK-PLUG.

Application filed November 22, 1917.

To all whom it may concern:

Be it known that I, JOSEPH S. OGARA, a citizen of the United States, residing at Lancaster,vv hio, in the county of Fairfield and State of Ohio, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specification.

This invention relates to spark-plugs of the type employed in connection with in ternal combustion engines, and the primary object of the invention is to provide a simple a'nd improved spark-plug wherein is embodied means of preventing the intense heat, evolved in an engine, from cracking, short circuiting or otherwise damaging the electrode insulating bushing, found in sparkplugs of common usage, whereby the life of the plug will be considerably extended and the general efficiency of the same signally improved.

With this and other objects in view, as will appear as the description proceeds, the invention consists inthe novel features of construction, combinations of elements and arrangement of parts hereinafter fully described and particularly pointed out in the appended claim.

In the drawing, wherein has been shown one of the preferred embodiments of the invention:

Figure 1. is a side elevation of the plug constructed in accordance with the preferred principles of the invention.

Fig. 2. ls a vertical, longitudinal section taken through the plug.

Fig. 3. is a detail perspective view of the tubular guard member employed for protecting the electrode bushing of the plug:

Fig. 4. is a fragmentary perspective view of the main electrode, showing the shield member carried thereby.

Similar characters of reference denote corresponding parts throughout the several views of the drawing.

Referring more particularly to the structural details of the invention, reference is to be had to the accompanying drawing whereinthe numeral 1 designates a spark-plug comprising the preferred form of the invention, the same being formed to include an outer metallic shell 2 having external threads 3, by means of which the plug may be threaded into its proper operative position within an engine. The upper part of the shell is, as usual, provided with fiat sur- Specifeation of Letters Patent.

Patented Nov. 26, 1918.

Serial No. 203,340.

faces for the reception of a suitable rotating. wrench or the like, whereby the convenient manipulation of the plug may be effected.

The shell is formed with an inner, centrally disposed, vertically 'extending opening A which latter' includes an enlarged threaded upper portion 4, and a considerably narrower lower portion 5, the juncture shoulder 6. A. vertically extended opening 10 passes diametrically through the bushing 7 and into which is positioned the main electrode 11 the upper extremity of` the latter bein(r extended beyond said bushing and is threaded for the reception of conductor securing nuts 12 and 13 of common construe; tion and utility. A sleeve 14 is rigidly secured to the electrode 11 and the upper end of which is adapted to engage with a shoulder 15 formed in the bushing 7, said shoulder being effected by a reduction in diameter in the opening 10, thus whe'nthe nut 12 is threaded down upon the Washer 16, the electrode 11 will be maintained in a substantially immovable or secured position within the bushing 7. The gaskets 8n may be provided upon the upper and lower surfaces of the flange 8 in order to permit of the required relative movement between said bushing and shell, due to temperature influences.

Coming now to the essence of the invention; it is a well known fact that the porcelain bushing of a spark-plug is extremely liable to become cracked or otherwise damaged by the intense heat generated by an internal combustion engine, thereby short circuiting the plug and rendering the same useless. oil will collect within the plug at points ad! jacent to the lower end of thc porcelain bushing, and when the engine is running, this accumulated matter under the excessive Frequently carbon or lubricating` heat of the engine will become highly heated operative position. Within the shell 2, the.

upper end of the same is provided With an annular oit-set lip 18, the latter being adapted to rest upon the shoulder 6 and is maintained in this position by the action of the nut 9 pressing down upon the dange 8, as

will be readily understood. The lower eK- tremity of the'guard member is tapered as at 19 and extends an appreciable distance below the bushing 7 so as to define a chamber 20. The Wall of the chamber 2O is spaced from the electrode 11 and rigidly secured to vthe lower extremity of the electrode 11, and spaced from the member 17, is a metallic shield element 21, which is provided with a sloping annular Wall 22.

From the foregoing description, it will be seen that the porcelain bushing is incased by the guard member 17 and is thereby prevented from coming into contact With the excessive heat of an explosive engine With which it may be associated, and also, due to the inclined Walls ol' the guard and shell members, the accumulation of carbon products thereon Will be rendered extremely difli.-v

cult, or at the outside this carbon deposit will be of negligible character, and may be readily removed from the plug. The electrode 11 hasa lower end, thereof, extending beyond the shield 21 so as to extend to a portion cao-adjacent to the grounding electrode 23 whereby the usual spark-gap 24 is resem/i established. lllhus it will be seen that the bushing 7 Will be spaced Jfrom the heat ofl the engine and will be maintained in a relatively cool condition, and thereby prevented from becoming cracked orn broken. Moreover, this guard member by enveloping the porcelain bushing, prevents the accumulated oil or carbon from short circuiting the plug, the member 21 serving as a baffle plate to prevent the oil from reaching the porcelain.

Having described the invention, what is claimed as patentable is:

A 'spark plug comprising an outer metallic shell having a vertically extending opening formed therein, said opening being of substantially the same diameterthroughout its lower portion, an angular shoulder forming a part of the Wall of said opening, an insulating core positioned Within said open ing and arranged for seating engagement with said shoulder, a metallic guard member situated to incase and protect the lower end of said core, said member' comprising a tubular body disposed to surround said core, a iiange formed on theupper end of said body and arranged to seat upon said shoulder, an apertured frusto-conical head formed upon the lower end of said body, said head being disposed beneath said core and arranged in the lower portion of said shell opening, an electrode carried by said core and having its lower extremity extended to pass through and beyond the apertured head of said body, and a substantially conical shield element carried by the extended end of said electrode and situated adjacent to the head of said guard member and having the rim thereof located contiguous to the annular Wall of the lower end of said shell opening.

ln testimony Whero'f l atliX my signature.

Josnrrr s. Toer/ina. 

